Spark-plug.



Patented Apr. 29, 1919.

swwwu @Rmnin A i! Wiil outrun snares earner curren TIMQEHEZJR'GROIll'IN, OF ST. LOUIS, MISSOURI.

SPARK-PLUG.

neonate.

To all whom it may concern Be it known that I, TIMOTHY P. CRONIN, a

citizen of the United States. of America, a

whereby the current is transformed and the spark intensified by the useof a number of electrodes arranged in series, with spark gaps betweenthem, one of the spark gaps being formed at the lower end or the plug inthe usual manner.

More specifically stated, an auxiliary spark gap is formed near the topof the spark plug so as to transform the current and produce a hotterspark at the main gap near the bottom of the plug. To obtain themostsatisfactory results, the auxiliary spark gap must be formed nearthe main. gap, for the increased voltage due to the transformation atthe auxiliary gap would otherwise be reduced or dissipated before thecurrent is transmitted to the main spark gap.

Hundreds of the specific devices herein shown and claimed have beenplaced in actual service on internal combustion engines, and, comparedwith ordinary spark plugs, the results have been a decided saving offuel, elimination of the trouble usually due to the presence of carbonor oil on the spark plugs, and, owing to the increased efficiency of thespark, the engine can be startt ed very easily.

The main electrodes in the engine cylinder are not short circuited orotherw1se 1njuriously afiected by carbon or oil, and the results haveclearly shown that a. comparatively lean explosive mixture can be usedin a cylinder equipped with the new device. In other words, the sparksderived from the new device thoroughly ignite a lean mixture,

and owing to the intensity of the sparks, the

combustion is so perfect that the usual err-- gine troubles due toimperfect combustion have been almost ent1rely eliminated. Consequently,more power is developed byan Specification of Letters Patent.

Application filed March 18, 1918. Serial No. 223,225.

automobile engine equipped with the new devices and the fuel consumptionis greatly reduced.

These statements are based upon results obtained in actual practice andnot upon th theory herein advanced, for I am aware that some of thestatements founded upon theoretical considerations may be more Or lessinaccurate.

These important results have been accomplished by the use or anair-tight chamber near the upper end of the spark plug and a series ofelectrodes, two of which terminate in said air-tight chamber to form anauxiliary spark gap therein. The air-tight chamber formed in aparticular manne1',-as will be hereinafter described, so as to-obtainthe desired results at a low cost. The highest eliiciency has beenobtained by forming a point at the terminal of the transmittingelectrode in the air-tight chamber and formmg a relatively large headatthe adjacent end of the receiving electrode. Actual service has shownthat this produces most desirable results, and according to myunderstanding of the theory of operation, the

smalltransmitting electrode opposing a relatively large face on thereceiving electrode eliminates resistance, and the current is car riedwith greater force to the main gap in the engine cylinder.

When the new device is first placed in service, the sparks at the maingap are red and somewhat inefficient, but they soon be co. ev 'blue andvery hot. The change is evidently due to the fact that the auxiliary gais formed in a sealed air-tight chamber, an at the beginning some of theconstituents of the air therein are consunied by the auxipary sparks.Thereafter, the auxiliary spams are not materially afiected by thepresence of air in the sealed chamber, and very hot blue sparks are thenproduced at the main gap.

The invention comprisesthe specific details involved in the productionof the Sim ple air-tight chamber, the peculiar relative proportions andconstruction of the electrodes therein, and other details ofconstructionwhereby a most efficient commercial article is produced at alow cost.

Figure I is a vertical section of a spark later, the

a o n 5 plug made in accordance with my invention,

also showing a portion of the engine cylinder to which the plug isapplied.

Fig. 11 is a horizontal section on line ill-11, Fig. l.

Fig. HT is a side elevation, partly in section, illustrating amodification.

The device shown in Figs. 1 and H comprises a tubular metallic member 1adapted to be screwed into the wall 2 or an internal combustion engine.A central insulator 3 is secured to the member 1 by means of a bushing4% screwed into the upper end of the member 1. A dome 5 is secured tothe upper end of the insulator 3 to form an airtight cham her at the topof the plug. The dome 5 has an inturned head 6 which lies in a recess atthe upper portion of the insulator. The metal dome and insulator arethus interlocked 'it othta." and they are preferably cen'i other bymeans of a cement that harden when subjected to a high 'teinp' ture. inassembling the parts the metal drone is preferably heated and therebyexp nded, and then permitted to contract I the upper portion of theinsuint being interposed between the insulator and the heated dome.

The metal at the center of the dome is preferably punched inwardly andthreaded to receive a screw 7 A jam nut 8 on the screw 7 is seatedagainst the top of the dome 5, and a binding nut 9 is fitted to thescrew 7 above the nut 8. 1O designates the terminal of a conductorleading to the spark plug, said terminal being clamped between the nuts8 and 9.

An intermediate electrode 11, located at the center of the insulator 3,extends from the air-tight chamber at the upper end of the plug to apoint near an electrode 12, cxtending from the tubular member l, at thelower end oi the plug. The intermediate electrode is separated from theend electrode 12 to form the main spark gap. An auxiliary spark gap is-formed between the lower end of the screw Y and the upper end of theintermediate electrode 11. The electrodes 7, 11 and 12 are so arrangedthat the spark gaps are in series with each other.- The lower end. ofthe screw 7 is pointed and a relatively large head 18 is: formed at theup per end of the electrode 11. The current passing from the screw, orcl .ctrode, 7 is transmitted from the pointed lower end to the largeface at the top of the head l3. By farming the ends of the electrodes 7and 11 in this manner, resistance is eliminated and the current iscarried with greater force to the main gap at the lower end of the plug.

To obtain the best results the screw 7 can be adjusted toward and awayfrom the'licad 13 so as to vary the width of the auxiliary spark gap,and the upper end of said screw is therefore notched to receive anadyusting ool. In Fig. Ill 1 have shown a. modification in the form oran attachment for an ordinary spark plug. The plug itself may beprovided with the usual electrode 12 at its lower end, and an electrode11 extending from an insulator 8. The electrodes 11' and 12' areseparated from each other to form the main spark gap. 15 designates theusual binding nut screwed onto the upper end of the electrode 11. Theattachment shown in Fi Ill comprises an insulator 16, a dome 55 securedthereto to form an airtight chamber, a screw 7 extending into theair-tight chamber,-nuts 8 and9 fitted tothe screw 7', an electrode 11"arranged in the insulator 1.6 and provided with a head 13 opposing thepointed lower end of the screw and a conductor 11 connecting theelectrode l1 to the electrode 11 at the center 01 the spark plug. Theconductor 11 is detachably secured to the spark plug by means of thebinding nut 15. 10 designates a. conductor clampcd between the nuts 8and 9. lit will be observed that the air-tight chamber of themodification and the electrodes therein are constructed like thecorresponding elements of Fig. 1. However, instead or an intermediateelectrode made of a single piece of material, the modification includesthe conductors 11, 11 and 11, connected together to transmit currentfrom the auxiliary spark gap to the main spark gap.

I clalmz A spark plug provided with an insulator, ametal dome cementedto the upper end of said insulator to provide a sealed airtight chamber,an upper electrode comprising a screw threaded into said dome andextending into said air-tight chamber, a lower electrode near the lowerend of said insulator. an intermediate electrode. arranged in saidinsulator and extending from said air,tight chamber to the lower end ofthe insulator, said intermediate electrode being separated from saidupper and lower ele'trodes to form a main spark gap at the lower end ofthe plug andan auxiliary spark gap in said air-tight chamber, the innerend of the threaded upper electrode being pointed and the intermediateelectrode being provided with an enlarged head opposing said pointedend, and a binding nut fitted to said threaded upper electrode.

in testimony that I claim the foregoing l hereunto afiix my signature.

T. l Clltl'hll'hl.

